1. Field
The present embodiments relate to a liquid crystal display having an in-cell backlight, and a method of manufacturing liquid crystal display having an in-cell backlight.
2. Related Art
Recently, the role of electronic display devices has become more important. A variety of electronic display devices have been widely used in various industry fields.
Generally, a LCD includes two substrates respectively having an electric-field generating electrode formed therein. The two substrates are disposed opposite to each other. A liquid crystal layer is formed between the two substrates. Liquid crystal molecules of the liquid crystal layer are moved by an electric field that is generated by applying voltage to the two electrodes, thus varying the transmittance of light. The LCD is adapted to display an image by controlling the transmittance of light.
The LCD device has been used in a variety of application fields because of characteristics, such as lightweight, a thin profile, and low-power consumption driving. The LCD device has been widely used in the fields of display devices, such as an instrument board indicating the progress direction, altitude, etc. of an aircraft, display devices of navigation for military use and vehicles, which requires high reliability at high altitudes. In addition, LCD devices have been used as office automated devices, such as personal computers, notebook computers and copy machines, portable devices, such as mobile phones and pagers, and so on.
The conventional LCD will be described below.
FIG. 1 is a cross-sectional view showing a general structure of a LCD. In FIG. 1, a Twisted Nematic (TN) mode employing a Thin Film Transistor (TFT), of the types of the LCD, is illustrated as an example.
The cross-sectional LCD comprises a liquid crystal panel 10 on which an image is displayed. A backlight unit 20 is disposed at the rear of the liquid crystal panel 10 and configured to provide a light source toward the liquid crystal panel 10. An external casing (not shown) contains the liquid crystal panel 10 and the backlight unit 20.
The liquid crystal panel 10 comprises a front substrate 11 and a rear substrate 15 opposite to each other, and a liquid crystal layer 13 formed therebetween. A black matrix 12a, a color filter layer 12b, an over-coat layer 12c and a common electrode 12d are formed under the front substrate 11.
The color filter layer 12b is partially overlapped with the black matrix 12a, so that red (R), green (G) and blue (B) are repeatedly constructed in a pixel region P.
In the rear substrate 15, a TFT (T) is formed, which comprises a gate electrode 15a, a gate insulating layer 15b, a semiconductor layer 15c, source and drain electrodes 15d, 15e, and a protection layer 15f in matrix form. The TFT (T) is connected to a pixel electrode that forms the pixel region P.
The liquid crystal layer 13 is provided with a spacer (not shown) for constantly maintaining a cell gap between the front substrate 11 and the rear substrate 15. A seal pattern (not shown) for maintaining the cell gap and preventing the leakage of the liquid crystal layer 13 is provided on the outer line of the liquid crystal layer 13.
Though not illustrated in the drawing, upper and lower alignment films are respectively formed on inner surfaces brought in contact with the liquid crystal layer 13 of the front substrate 11 and the rear substrate 15.
The backlight unit 20, as illustrated in FIG. 1, is disposed at the rear of the liquid crystal panel 10, and functions to provide light toward the liquid crystal panel 10. Backlight units 20 are classified into a direct type or an edge type backlight unit depending on the installation structure (location) of a light source that emits light.
A direct type backlight unit includes a light source disposed at the front of the panel. The edge type backlight unit includes a light source disposed laterally to the panel.
The direct type backlight unit will be described in detail. As illustrated in FIG. 1, the direct type backlight unit includes a plurality of lamps 21 arranged in a row immediately below the rear of the liquid crystal panel 10. A reflection plate 23 is disposed under the plurality of lamps 21. An optical film 25 is disposed over the lamps 21 and configured to polarize light emitted from the lamps 21. Accordingly, the light emitted from the lamps 21 can be provided to the front of the liquid crystal panel 10.
An edge type backlight unit includes an additional waveguide provided at the rear of the liquid crystal panel 10, and lamps are installed laterally to the waveguide. Thus, light incident from the side of the waveguide can be refracted and provided to the front of the liquid crystal panel 10.
The conventional LCD constructed above is completed through a process of manufacturing the liquid crystal panel 10, a process of manufacturing the backlight unit 20, and a process of assembling the liquid crystal panel 10 and the backlight unit 20.
For example, the backlight unit 20 is manufactured as an external module that is separate from the process of manufacturing the liquid crystal panel 10, and is subsequently assembled with the liquid crystal panel 10, thus completing the LCD.
The conventional LCD is problematic in that it requires a relatively long process time in the manufacture process and is complicated in the process procedure. The conventional LCD is problematic in that it is difficult to achieve an ultra-thin because the backlight unit 20 is mounted at the rear of the liquid crystal panel 10.